There are general conventional methods of growing a plant. In one method, the growth of the roots is restricted but the growth of a number of root hairs is promoted to make the cultivation after transplantation better by burying the plant in the ground together with a plant pot. In this method, the pot has a number of penetrating holes and is made from a synthetic resin which is does not carrode or deteriorate in the ground. According to the cultivation method using such a plant pot, the root hairs grow through the small holes of the pot wall. When the plant is removed from the pot for transplantation, difficulty may be encountered which will cause the root hairs to cling to the small holes of the pot, and the plant cannot be removed from the pot successfully without destroying the soil near the plant. It is a disadvantage of this conventional method that, if such soil is destroyed, the root hairs which have been grown for a long time may be destroyed and/or separated from the soil in pot, the growth after transplantation is severely disturbed.